O’Neill said: “Stiliyan started brilliantly for us – as I was expecting – and did ever so well in the games early on against West Ham and Watford amongst others.
“That is the kind of form he would generally show pretty consistently. That’s what I expect of him. He had a bit of a lull after that good start – but he is coming back.
“He had a bit of a hamstring problem after being excellent for us in the win at Everton and, when he came back against Middlesbrough the weekend before last, it was pretty tight during the game.
“Psychologically people do concern themselves coming back after a hamstring problem but that game did him the world of good. He is getting there for us and will be a big asset for this club.”
O’Neill added: “I’ve got no problems with him. Yes, I would have expected him to have scored a goal or two by now but that will come.
“To score a goal or two will give him a natural boost of confidence – but he is not short of confidence.
“People have to adapt to the Premiership and Stiliyan is such a character that I would expect him to adapt very quickly – and he will do.
“We’ve seen glimpses of what he is capable of doing and he will hit that consistently when everything is right.”